Floating type hydraulic piston



' Jan. 19, 1943. i J. w, HATcH 2,308,956

FLOATING TYPE HYDRAULIC PISTON Filed March 23. 1940 E@ I if INVENTO R ATTORN EYS Patented Jan. 19, 1943 2,308,956 FLOATING TYPE HYDRAULIC PISTON James Firestone W. Hatch, Akron, Ohio, assigner to The Tire & Rubber Company, Akron,

. Ohio, a corporation of Ohio Application March 23, 1940, Serial No. 325,604

(Cl. Iso-54.6)

6 Claims.

'I'his invention relates to hydraulic pressure systems and, more especially, to a Iioating type hydraulic piston for use in such pressure systems.

Heretofore in hydraulic brake constructions, with which the present invention is particularly adapted to be used, a master pressure chamber has been provided. 'I'his pressure chamber normally is positioned immediately adjacent the brake pedal arm, or other means used to apply the brakes manually, which arm or means usually has arcuate movement. A suitable piston is provided in the pressure chamber, which piston is adapted to receive only axial reciprocating motion so that some intermediate connecting member is necessary to connect the piston rod to the brake application means so that the slight arcuate-movement usually produced thereby is transformed into pure axial reciprocating motion before being applied to the piston rod.

An important object of this invention resides in the provision of an improved piston comprising a rigid head and resilient walls, the resilient walls being adapted to engage the walls of an associated cylinder in uid sealing relation therewith while permitting universal movement between the piston head and the sealing walls of the cylinder, whereby the piston may be actuated by a rod having one end xed to the head and an opposite end engaging a driving member transcribing an arcuate path, without breaking the sealing relation of said piston and cylinder.

A further object is to provide an improved piston having a rigid head adapted to engage the walls of an associated cylinder in substantial line contact, whereby to minimize vibration and prevent lateral movement of the piston during reciprocation, and resilient piston walls engaging the cylinder walls in fluid-sealing relation there; with to allow relative movement betweenthe piston head and walls without disturbing the seal between the piston and cylinder walls. Another object of the invention is to provide an improved seal in a vpressure chamber whereby a piston head can be given slight arcuate movement without breaking the seal formed thereby in the chamber or without injuring itself or the walls of the pressure chamber.

A further object of the invention is to provide a. novel and improved floating type hydraulic piston which is easily and inexpensively con-` structed, but which has a long, serviceable life.

The foregoing and other objects will be manifest from the specification. Y

The invention will be described with particular having a head portion,

vided to aid in mounting the pressure chamber l I0 in its operable position upon frame means (not shown). Any suitable incompressible fluid is received inthe pressure chamber I0. The pressure chamber I0 receives a piston I2 therein |2b of maximum diameter at the forward or leading margin I3 thereof, for engagement with the cylinder walls. Note that the remaining edge portion of the pistonhead I2b, that is of substantially the same diameter as the leading surface I3, is substantially arcuate in contour, the arc dened by the edge of the piston head I2 being centered at the center of the leading surface I3 whereby the piston head I2 is only in substantially line, or circular contact with the wall of the pressure chamber I0.

This construction is a feature of the present invention. A sealing cup I4 is associated with the surface I3 and extends over and covers'same. This sealing cup has a cylindrical wall I5 extending forwardly therefrom to engage the walls of cylinderIIl in uid sealing relation. Usually the sealing cup is made from rubber and is vulcanized to the piston head I2. The piston head I2 is of reduced diameter adjacent the rear thereof to provide a. connection block I2c having a cylindrical recess I2a formed therein which receives the end of a piston rod I6. This piston rod has an annular groove` I'I formed therein which receives an inwardly extending annular boss I8 formed at the rear of the piston head I2 whereby the piston rod and piston head are held in engagement.

Suitable means connect the free end Ilia of the piston rod I6 with means actuated by the brake control pedal normally present in vehicles.

In accordance with the present invention, these means may include a pressure arm I9, having a bifurcated end 2| that is pivotally mounted on a pin 22. This pin is journalled in an extended anchor arm 23 carried by the pressure chamber I0, which arm 23 may aid in mounting the pressure chamber. A pintle 24 extends through a hole 25 formed in the pressure arm I9 and through a hole 26 formed in the end Isa of the piston rod I 6 to secure the piston rod directly to the pressure arm I9.

The piston rod I6 is sealed in the pressure chamber Ill and its outward movement relative thereto is limited by a rubber sealing ring 21 that is received in the end of the pressure chamber I0. This sealing ring 21 is positioned by annular washers 28 and 29 which, in turn, are held in place by abutting on a shoulder 3| formed in the bore of the pressure chamber I and by pins 32 extending through the pressure chamber I0, respectively.

From the foregoing, it will be observed that the piston rod I 6 is xedly secured to, or possibly integral with the piston head I2 and that the piston rod is given a substantially reciprocal movement in the pressure chamber I0 through the pressure arm I9. The pivotal movement in the pressure arm I9, since the end of the piston rod isf'xedly secured thereto, also move the end of thepiston rod through a small arc relative to the axis of the pressure chamber Ill. The

slight arcuate movement of the piston rod does not damage or destroy the seal formed in the pressure chamber by the piston head I2 and the rubber sealing cup I4 as the rubber member is forced back againstthe piston head by uid within the piston chamber. Also, the piston head I2 is of such construction that slight arcuate movement thereof does not force any portion of the piston head into the chamber wall so as to scratch or mar same. Hence it is seen that the present construction is simpler than and possesses .advantages over constructions shown in the prior art for similar purposes. An important advantage resides in the minimization of piston vibration and noise due to the piston being snuggly engaged with a minimum metallic contact between piston and cylinder.

The remaining parts of the master cylinder for the brake are of substantially standard construc- -tion and include a valve head 4I that is secured to the piston vhead I2 by a chain 42. A spring 43 surrounds the chain 42 and bears against the valve head 4I and the piston head I2 to retain same apart. This valve head 4I is adapted to engage with a sealing head 44 suitably secured in the exit end of the pressure chamber I Il. This sealing head 44 has a substantially axially positioned inlet port 45 therein which connects to a suitable reservoir (not shown) for the nuid means within the pressure chamber I 0. An annular boss 46 is formed around the port 45 and is designed to engage with an end member 41 carried on the forward side of the valve head 4I. An outlet port 48 is formed in the sealing head 44 adjacent the periphery thereof. 'I'his outlet port 48 connects to suitable means (not shown) which transfer uid from the pressure chamber I0 to the separate brake shoes (not shown) operated from the pressure chamber I0. 'Ihen upon forward movement of the piston head I Z, the spring 43 forces the valve head 4I to seat against the sealing head 44, which operation forces a small volume of iiuid from the pressure chamber I0 through the inlet port 45. Then after the boss 46 has been seated in the end member 41, uid can be forced from the pressure chamber I0 only around the' periphery of the valve head 4I and through the outlet port 48, which effects the desired braking action.

While a written description and illustration of one embodiment of the invention is disclosed herein, it will be understood that modications can be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. In a duid pressure device, the combination with a cylinder, of a piston disposed for reciprocation therein and comprising a disk-like rigid head having a planiform leading surface and transversely arcuate side walls, a piston rod xedly connected to the trailing side of said head, and a resilient sealing member bonded to the leading side thereof and provided with wall portions of substantial length engaging the cylinder walls in continuous fluid sealing relation for a substantial distance along said cylinder wall, said head margins engaging the cylinder walls in substantially line contact, whereby to allow universal movement of said head in respect to said walls without disturbing the sealing engagement between the resilient member and the walls of the cylinder.

2. A cylinder and piston construction comprising a'cylinder having a sealing head provided with an inlet port, a piston in said cylinder, said like head portion being at its leading edge, the t relative diameter of the disc like head and the inside of the cylinder being such that the disc like head makes substantial line contact with the wall of the cylinder, a cup-shaped rubber-like sealing member attached to the leading face of said piston head, the outside diameter of said sealing member being not less than the inside diameter of said cylinder, whereby the peripheral surface ofn the sides of said sealing member is in iuid sealing engagement with the inside surface of said cylinder along the entireylength of said sealing member, the sides of said sealing member being supported against-lateral pressure by the inner surface of said cylinder, and whereby the entire cross-sectional area oi said sealing member is supported by the leading face of said piston head against longitudinal pressure.

3. In combination with a cylinder and inname' and piston head whereby said valve and piston heads are held spaced apart but flexibly connected, so that the valve head may be always effectively seated against said port as the pistonhead and piston rod are oscillated through an arc with respect to said cylinder during reciprocation of the piston.

4. In combination with a piston and cylinder construction wherein the axis of the piston is oscillated or tilted during reciprocation, a disclike piston head having its maximum diameter at its leading edge, the said diameter of the piston head-being 'such that said leading edge makes linecontact with the inner wall of the cylinder when the piston head is in an untilted position, a cup-shaped sealing member composed of a readily distortable material attached to the leading face of said piston head with the peripheral surface of said sealing member in continuous contact with the inner surface of the wall of said and cylinder as the line contactv between thel cylinder and piston is broken when the latter is tilted.

5. In combination with a piston andA cylinder construction, a disc-like piston head having its maximum diameter at its leading edge,l the said diameter of the piston head being such that said leading edge makes substantially a line contact with the inner wall of the cylinder, a cup-shaped sealing member composed of readily distortable material attached to the leading face of said piston head and extending to its marginal edge whereby the piston head supports all of the material composing said sealing member against distortion by longitudinal pressure exerted on said cup-shaped sealing member.

6. A cylinder and piston construction comprising a cylinder having a sealing head provided with an inlet port, a piston in said cylinder, said piston having a disc-like rigid head portion, the

maximum diameter of said disc-like head portion being at its leading edge, the relative diameter of the disc-like head and the inside of the cylinder being such that only the forward edge of saiddisc-like head contacts the wall of the cylinder, a cup-shaped sealing member of substantial length associated with the leading face of said piston head, the outside diameter of said cylinder being such whereby the peripheral surface of the sides of said sealing member are in fluid sealing engagement with the inside surface of said cylinder along the entire length of said sealing member', the sides of said sealing member being supported against lateral pressure by the inner surface of said cylinder, and whereby the entire cross-sectional area of said sealing member is supported by the leading face of said piston head against longitudinal pressure.

JAMES W. HATCH. 

